Pachymetry and intraocular pressure measurement by corneal visualization Scheimpflug technology (Corvis ST):A clinical comparison to the gold standard.,Pachymetrie und Augeninnendruckmessung mittels Corneal-Visualization-Scheimpflug-Technologie (Corvis ST): Ein klinischer Vergleich zum Goldstandard

BACKGROUND: Analyses regarding accuracy and reproducibility of intraocular pressure (IOP) measurements and pachymetry with corneal visualization Scheimpflug technology (Corvis ST®, CST).

MATERIAL UND METHODS: Retrospective analysis of 72 eyes with primary open angle glaucoma (POAG) and ocular hypertension (OHT) with no prior surgery or other pathology. The results of Goldmann applanation tonometry (GAT), non-contact tonometry (NCT) and ultrasound pachymetry (USP) were compared with repeat measurements with CST. For statistical analyses the t-test and Bland-Altman plots were applied.

RESULTS: The mean IOP was 15.5 ± 4.4 mmHg (CST), 14.8 ± 4.4 mmHg (GAT) and 15.6 ± 4.8 mmHg (NCT). The results of GAT and CST as well as GAT and NCT demonstrated statistically significant differences (p < 0.001) whereas NCT and CST displayed no significant differences in IOP (p = 0.72). The mean differences between the repeat measurements were 0.35 ± 1.7 mmHg (CST) and 0.04 ± 0.85 mmHg (GAT). The mean CST pachymetry results showed 551.3 ± 46.5 µm and the USP 526.5 ± 46.4 µm (p < 0.001). The mean difference between the repeated CST measurements was 24.8 ± 21 µm. No repeat measurement data were available for USP.

CONCLUSION: The CST is a new device for simultaneously measuring the IOP, pachymetry and biomechanical properties of the cornea. Whether the deviations in the IOP measured by CST and CST pachymetry from the manually performed gold standard has to be evaluated as deficient, tolerable or maybe as an improvement, has to be evaluated in further studies. Because of the automated and contact-free measurement method as well as the potential for simultaneously analyzing biomechanical properties of the cornea, the CST is a device that might help the quest for measuring the 'true' IOP.